As part of its survey, Checkbook.org compared prices for Wal-Mart and Target in D.C. and the suburbs and found both stores charge more than suburban counterparts.

Wal-Mart spokesman John Forrest Ales gave this response:

“Based on the stores that were included in the study, we’re proud Walmart is the supermarket with the lowest overall prices for families both in the district and surrounding areas. While operational costs and other factors naturally vary by location, our commitment to everyday low prices never changes.”

A Safeway representative gave this response:

"Limited item price comparisons rarely provide consumers with a full picture of prices across a typical grocery store. Safeway carries more than 45,000 products in any one of our stores. A comparison of a small number of items does not provide consumers with a true picture of prices across the entire store nor does it appropriately reflect the full savings that our customers enjoy. In addition to Safeway Club Card discounts, our customers can benefit from our extensive selection lower-priced, high-quality private label products in practically every product category across the store — not just 17 percent of products, as the Checkbook.org survey accounted for — and Just for U discounts, which offer individualized savings on the products that each customer purchases most often."